Color Banding on ASUS PB278 screen even after applying an Override to be in RGB mode - color depth issue?

[douira]

I'm running macOS Catalina 10.15.2 and pretty much everything except for this color banding issue works. All gradients are displayed with lines in them instead of smoothly. I've heard this has something to do with the color mode being wrong. So I used this script: https://gist.github.com/ejdyksen/8302862 to "fix EDID" problems.

As you can see, the screen is being reported as RGB but the color banding issue persists. Is the problem that my screen has a higher color depth than my computer is outputting or the other way around? What can I do to fix this? I can provide more diagnostic and configuration data where necessary.

Strangely enough, when I take a screenshot of a color-banded area (in particular where a blur effect is applied) and look at the uncompressed image on my phone I can also make out the color banding. I've attached such a screenshot.

This is the info about my screen from the System Report:

Radeon RX Vega 56:
Chipset Model: Radeon RX Vega 56
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 8 GB
Vendor: AMD (0x1002)
Device ID: 0x687f
Revision ID: 0x00c3
Metal: Supported, feature set macOS GPUFamily2 v1

Display with forced RGB mode (EDID override):
Resolution: 2560x1440 (QHD/WQHD - Wide Quad High Definition)
UI Looks like: 2560 x 1440 @ 59 Hz
Framebuffer Depth: 30-Bit Colour (ARGB2101010)
Display Serial Number: ****
Main Display: Yes
Connection Type: DisplayPort

 

[Bustycat]

This issue persists for some macOS users (including real Macs). You could also try this.

<< Solved >> - Forcing RGB mode for problematic displays

Is that related to the driver of RX 580? Those don’t happen at all on Windows. Yes, it tells macOS which driver to use.

www.tonymacx86.com

 

[douira]

I did that and restarted at least 4 times and it sadly didn't change anything. I also tried using the kext that Hackintool generated but that didn't help either. Connecting my monitor with an HDMI cable also didn't solve the problem and produced the same color banding. So is this an issue with my screen or with macOS?

Edit: this issue also happens when I connect my MacBookPro via HDMI to my screen. So this seems to be a general screen/macOS issue here.

macOS seems to think my screen supports 10 Bit color depth for each channel although it only supports 8 Bit. This might be the problem... But idk how I should solve it.

 

[Bustycat]

I did that and restarted at least 4 times and it sadly didn't change anything. I also tried using the kext that Hackintool generated but that didn't help either. Connecting my monitor with an HDMI cable also didn't solve the problem and produced the same color banding. So is this an issue with my screen or with macOS?

Edit: this issue also happens when I connect my MacBookPro via HDMI to my screen. So this seems to be a general screen/macOS issue here.

macOS seems to think my screen supports 10 Bit color depth for each channel although it only supports 8 Bit. This might be the problem... But idk how I should solve it.

Maybe you could try to select a different depth manually.

ResXtreme

ResXtreme is a Mac display mode utility created by the author of EasyRes.

resxtreme.com

 

[douira]

I downloaded ResXtreme and tried it out. If I choose a 10 Bit/Sample (whatever that means) it gets worse and I can also see heavy color banding on the Finder sidebar which didn't happen all the time before (it did sometimes). Choosing an 8 Bit/Sample makes it like it was before. So the problem is amplified by choosing the wrong setting here.

 

[Bustycat]

Hmm... Have you tried that for Windows?

 

[douira]

I don't have a Windows machine to try this out with but I could run a Linux live distro from a USB stick and see if the color banding happens there too. I'll try to make a test image that clearly displays the banding. I'd like to add that I don't remember having this kind of color banding before I switched from an NVIDIA graphics card to the current AMD graphics card I have now.

 

[douira]

The color banding does not happen on Ubuntu. This seems to be a macOS issue in combination with my current screen and graphics card. I'm going to check if this also happens with a different screen.